Theft of fuel is a major problem for operators of service stations that dispense gasoline. Would-be thieves resort to many different measures to remove or destroy the outer shell of the fuel pump in an effort to access various mechanisms of the pump that are normally inaccessible due to the shell. One target of thieves is one or more metering devices housed within the shell that convert a flow of fuel to an electronic signal indicating an amount of fuel being dispensed. The metering device allows the service station to charge the customer an amount of money that is proportionate to the amount of fuel dispensed. However, if this metering device can be disengaged (by destruction, separation, damaging, or other ways), no electronic signal is produced and fuel can be dispensed by the thief without a dollar value being assigned to the fuel removed from the pump. Of course, with fuel currently varying from about $2.50 per gallon to about $5.00 per gallon, loss of fuel to theft is highly undesirable to the service station operators.
Prior-art fuel theft detection systems disable fuel dispensers once tampering is detected by cutting off power to the entire dispenser. This method of disablement is disadvantageous because disabling power to the entire dispenser also shuts down the sensitive computer equipment, which contains previous transaction information, calibration information, and others. In addition, dispenser communication to the nearby in-station cashier is disabled. The dispenser simply goes dead.
Some prior-art dispenser security systems simply cut power to the control valve located within a dispenser while leaving the rest of the dispenser under power. This method is disadvantageous because shutting off the valve does not shut off the submerged turbine pump (STP), does not stop the pumping unit, does not finalize the sale, does not notify the pump controller of the shut down, which in turn changes an indicator for the cashier or attendant at the control system, and could result dangerous voltage transients at the time of switching.
Therefore, a need exists to overcome the problems with the prior art as discussed above.